84 STAT. ]
PUBLIC LAW 91-258-^AY 21, 1970
(A) IN GENERAL.—It shall be the duty of the Secretary of the Treasury to invest such portion of the Trust Fund as is not, in his judgment, required to meet current withdrawals. Such investments may be made only in interest-bearing obligations of the United States or in obligations guaranteed as to both principal and interest by the L"'nited States. For such purpose, such obligations may be acquired (i) on original issue at the issue price, or (ii) by purchase of outstanding obligations at the market price. The purposes for which obligations of the United States may be issued under the Second Liberty Bond Act, as amended, are hereby extended to authorize the issuance at par of special obligations exclusively to the Trust Fund. Such special obligations shall bear interest at a rate equal to the average rate of interest, computed as to the end of the calendar month next preceding the date of such issue, borne by all marketable interest-bearing obligations of the United States then forming a part of the Public Debt; except that where such average rate is not a multiple of one-eighth of 1 percent, the rate of interest of such special obligations shall be the multiple of one-eighth of 1 percent next lower than such average rate. Such special obligations shall be issued only if the Secretary of the Treasury determines that the purchase of other interestbearing obligations of the Ignited States, or of obligations guaranteed as to both principal and interest by the United States on original issue or at the market price, is not in the public interest.
40 Stat. 2 8 8. 31 USC 774.
(B) SALE OF OBLIGATIONS.—Any obligation acquired by the
Trust Fund (except special obligations issued exclusively to the Trust Fund) may be sold by the Secretary of the Treasury at the market price, and such special obligations may be redeemed at par plus accrued interest. (C) INTEREST ON CERTAIN PROCEEDS.—The interest on, and
the proceeds from the sale or redemption of, any obligations held in the Trust Fund shall be credited to and form a part of the Trust Fund. (3) APPLICABILITY OF PARAGRAPH (2).—Paragraph (2) of this subsection shall not apply until the beginning of the fiscal year immediately following the first fiscal year beginning after June 30, 1970, in which the receipts of the Trust Fund under subsection (b) exceed 80 percent of the expenditures from the Trust Fund under subsection (f)(1). (f) EXPENDITURES FROM TRUST F U N D. —
(1) x^iRPORT AND AIRWAY PROGRAM.—Amouuts in the Trust Fund shall be available, as provided by appropriation Acts, for making expenditures after June 30, 1970, and before July 1, 1980, to meet those obligations of the United States— (A) hereafter incurred under title I of this Act (as in effect Ante, p. 219. on the date of the enactment of this Act), or incurred at any time before July 1, 1970, under the Federal Airport Act (49 U.S.C., sec. 1101 et seq.); eo Stat. i7o (B) heretofore or hereafter incurred under the Federal Aviation Act of 1958, as amended (49 I L S. C, sec. 1301 et seq.), which are attributable to planning, research and ^2 Stat. 731